Method for producing blank shells



Feb. 8, 1966 w, CLAS 3,233,505

METHOD FOR PRODUCING BLANK SHELLS Original Filed Oct. 4, 1963 Pdafde/ We I NVENTOR ATTORNEYS United States Patent Ofice 3,233,505 Patented Feb. 8, 1966 P a Claims. (Cl. 86-12) This application is a division of -applicants co-pending application Serial No. S14-,G38 filed October 4, 1963.

Blank shells have previously been made by pressing one or more plugs made of cork, compressed cork or the like into the shell case above the powder charge as tamping means and cementing the plug or plugs by means of a suitable adhesive, for example shellac. The plugs employed have heretofore been made in a separate operation, for example, from granulated cork and a suitable binding agent.

Vlt is among the objects of this invention to pro-duce tamping means for a blank shell which, on firing, is reduced to particles substantially smaller than has been the case lwith known tamping means. A specific object is to provide tamping means which, after firing the blank shell, does not form residues on the inside of the shell case, and therefore which allows the case to be -easily cleaned ready for refilling, thus avoiding the considerable amount of work involved in cleaning the used shell cases of known blankl shells. A further object of the invention is to produce blank shells which can be packed immediately after manufacture', and in particular which can be packed before the tarnping means has hardened.

Other obiects and advantages of the invention will be apparent from the ensuing description and from the example illustrating the invention.

The present invention provides la blank shell comprisinga shell case, powder charge and tamping means for the powder charge, wherein the tamping means is formed by introducing a nompreformed mixture into the shell case, forming the mixture into a plug by light mechanical pressure, and allowing the mixture to harden, and wherein the said mixture contains the following components:

(a) an epoxy resin (b) a hardening agent for this resin which effects the hardening without the supply of heat from outside (c) a filler comprising a comminuted sott vulcanisate of natural or synthetic rubber which contains fibrous material.

The term epoxy resins is applied, as is well known, to hardenable compounds containing more than one epoxy group in the molecule. Such resins can be prepared, for example, Vby reacting polyvalent phenols with epichlorohydrin or by reacting salts of polybasic aromatic carboxylic acids with epichlorohydrin. Also suitable for the method according to the invention are epoxy resins produced by other known methods, for example by epoxidation of suitable unsaturated compounds with the aid of performic acid or peracetic acid.

Conventional so-called cold hardeners may be employed as hardeners for the epoxy resins, that is, compoundswhich effect the hardening without the supply of heat from outside. Suitable for this purpose are, inter alia,` compounds containing amino groups, for example, aliphatic dior polyamines, such as diethylenetriamine, triethylenetetramine and others. Especially suitable in the present invention are polyamides containing a sufficient number of free amino groups. The latter group of hardeners can therefore be used with advantages for the method according to the invention, because when these are employed the hardening proceeds without any relatively marked spontaneous heating of the tamping mass.

The proportions of epoxy resin and hardener can be obtained from the known formulae for these commercial products.

Comminuted soft vulcanizates of natural or synthetic rubber which contain fibrous material are added to the mixture of epoxy resin and hardener as a filler. The rubber may contain conventional additives, such as, for example, zinc oxide or carbon black. Preferably, so-called carcass meal is employed as a filler. The term carcass meal is applied, as is well known, to the comminution products of the side walls of used motor vehicle tires, which contain a relatively high proportion of fibrous material. The grain size of commercial carcass meal is of the order of magnitude of 0.5-3 mm. The carcass meal contains as fibrous material those fibres from which the so-called tire cord was constructed.

Cotton was originally employed for the production of tire cords. Later, a change was made to the use of nylon fibres, if required admixed with cotton, for this purpose. Recently, polyester fibres, for example, the fibres produced by the esten'fication of ethylene glycol with terephthalic acid and subsequent spinning of the polyester obtained andwhich have become known under trade names such as Terylene, Daeron, Trevira and others, have been employed for this purpose.

For the production of blank shells in accordance with the invention, commercial carcass meal or rubber meal of various particle sizes containing fibrous material may be used.

The ratio of the quantity of the mixture of resin and hardener to the quantity of the filler in the mixture employed for tamping the powder charge may vary within wide limits. These limits depend on the particle size of the filler employed andfon the properties, in particular the viscosity, of the mixture of epoxy resin and hardener. The mixture `of the three constituents, when introduced into the shell case, must be capable of being shaped or moulded at a moderate pressure and, moreover, suiciently sticky to render possible firm `adhesion of the tamping means to the wall of the shell case before hardening.

When relatively highly viscous epoxy resins are employed, it is possible to increase the proportion of filler in the mixture by adding to the mixture so-called reactive diluents, for example, phenyl glycide ether or suitable surface-active substances such as, for example, addition products of ethylene oxide and long-chained alcohols or carboxylic acids, thereby reducing the viscosity of the mixture. On the other hand, the mixture should not be too highly fluid before the moulding operation. Thev appropriate consistency, and thereby the correct ratio between the mixture of resin and hardener and the filler, can be determined in any given instance by a number of preliminary tests. Preferably, about 1-7 parts of the ller are used to about 1 part of the mixture of epoxy resin and hardener (the parts being by weight), although this guide is not intended to constitute la restriction.

To produce the tamping mass, the resin is mixed in a mixing apparatus suited to its viscosity, for example, a kneader, with the hardener and the filler is then added. Of course, the filler may be first mixed with the resin or with the hardener andi the remaining component then added. It is possible for the addition of the remaining component to be edected by, @for example, spraying.

Conventional shell cases and types of powder may be employed for producing the blank shells according to the invention. It is advantageous to cover the powder charge lby a protective covering, for example, by a cardboard cover. After the polwder charge has been put in and, if required, covered, the unpreformed mixture of epoxy resin, hardener and filler employed for tamping purposes is placed in the shell case. 'Ihe quantity of tarnping matelrial may vary within Wide limits. F or a blank shell for guns of 9 cm. calibre, the required quantity is between .about 100 and 300 gra-ms. For larger and smaller calibres correspondingly larger or smaller quantities are required. The optimum quantity can be determined easily for each case by preliminary tests.

The pastealike tamfping material introduced into the shell case is shaped by light mechanical pressure so that it forms an air-tight plug of approximately uniform thickness sealing the powder charge oi at the top and which, after hardening, adheres tightly to the wall of the sheil case. The hardening of the plug takes place subsequently without supplying heat from outside.

In practical tiring tests of blank shells according to the invention, it has beenyfound that the properties of the blank shells, such as a loud explosion similar to that of a real shot `and an intense muzzle flash, are not unfavorably affected by the Itamping means used in thel blank shells. After tiring, the gun lbarrels were in aultless condition.

The .following example illustrates the invention.

200 grams of .a commercially available epoxy resin obtained by reacting diphenylol propane with e-pichlorohydrin were mixed with 100 grams of a polyamide containing free amino groups (a commercial product known as Versamid 140). The mixture of resin and hardener was then mixed with 700 grams of a commercial carcass meal.

600 lgrams ott nitrocellulose in the form of strips 2 om. wide `and 0.5 mm. thick were crumbled into a shell case designed for guns of 10.5 cm. cali-bre. 300 Igrams of the above-described mixture of epoxy resin, hardener and ller were then placed on the cover and formed into a plug `of uniform thickness by light mechanical pressure. The shell case was thereafter packed immediately.

The above procedure Was repeated, but 1500 grams of carcass mal were mixed with the 300 grams of the mixture of epoxy resin and hardener.

In both cases very serviceable blank shells were obtained. Muzzle flash Iand explosion corresponded substantially to those of a live round. Affter tiring, no solid constituents whatsoever could be found in the front of the barrel. No residues Icould be seen in the ygun barrel. There -Were no residues of the ramping mass on the wall of the shell case, so that lthe cases could be reiilled without troublesome cleaning measures.

The accompanying drawing illustrates the invention by means of three gures, of which FIGS. le3 are side elevations partly in section showing the structure of the blank shell with the tamping means. ln the gures of drawing, l indicates the blank shell and 2 is the powder charge. in FlGS. l and 3, numerals 3 and 6 indicate the tamping means and in FIG. 2, the tam-ping means 4 is provided with a protective cover 5 which may be cornposed ot' cardboard.

lll.

I claim:

`il. A process `for the manufacture of blank shells, comprising placing a powder charge within `a shell case, introducing ra nonpretormed mixture ot an epoxy resin, a hardening agent for the resin which effects the hardening without the supply of heat from outside, and a ller cornprising a comminuted soit vulcanizate of a natural or synthetic rubber which contains brous material into the shell case above the powder charge, shaping the mixture by light mechanical pressure to -form a plug, and allowing said mixture to harden to form tamping means for the powder charge.

2. A process according to claim l, in which the further step is provided of covering the said ypowder charge by a protective covering before the introduction of the said mixture into the shell case.

3. A process according to claim A1, in which a reactive diluent is incorporated into said non-preformed mixture and selected from the group consisting of phenyl glycide ether, `addition products of ethylene oxide and longchained alcohols, and addition products of ethylene oxide and long-chained carboxylic acids.

4. A process -for the manufacture of blank shells, comprising placing a powder charge `within a shell case, introducing a nonapreforrned mixture of an epoxy resin and a hardening agent therefore to effect the hardening exclusive of heat and a filler comprising a comminuted vulcanizate of a natural rubber containing brous material into the shell case `above the powder charge, applying pressure to the mixture to shape it to :form a plug, and hardening the mixture to 4form tamping means for the powder charge.

5. A process for the manufacture of blank shells, comprising placing a powder charge within a shell case, introducing a non-pretormed mixture of an epoxy resin and a hardening agent therefore to eiect the hardening exclusive of heat and a lfiller comprising a comminuted vulcanizate of a synthetic rubber containing fibrous material into the shell case above the powder charge, applying pressure to the mixture to shape it to for-m a plug, and hardening the mixture to form tamping means for the powder charge.

References Cited by the Examiner FOREGN PATENTS 582,350 11/1946 Great Britain.

SAMUEL FENBERG, Primary Examiner.

BENIAMIN A. BGRCHELT, Examiner. 

1. A PROCESS FOR THE MANUFACTURE OF BLANK SHELLS, COMPRISING PLACING A POWDER CHARGE WITHIN A SHELL CASE, INTRODUCING A NON-PREFORMED MIXTURE OF AN EPOXY RESIN, A HARDENING AGENT FOR THE RESIN WHICH EFFECTS THE HARDENING WITHOUT THE SUPPLY OF HEAT FROM OUTSIDE, AND A FILLER COMPRISING A COMMINUTED SOFT VULCANIZATE OF A NATURAL OR SYNTHETIC RUBBER WICH CONTAINS FIBROUS MATERIAL INTO THE SHELL CASE ABOVE THE POWDER CHARGE, SHAPING THE MIXTURE BY LIGHT MECHANICAL PRESSURE TO FORM A PLUG, AND ALLOWING SAID MIXTURE TO HARDEN TO FORM TAMPING MEANS FOR THE POWDER CHARGE. 